It is frequently desirable to provide regulated DC current to a drive control element such as an electro-magnetic coil or a motor. Typically, control of the regulated current depends primarily or the characteristics of the drive control element. These characteristics vary from system to system and are not normally known when the control system is designed and constructed. A system designer is therefore forced to design using typical, rather than actual characteristics of the drive control element.
While such control is adequate, in some systems, it would be beneficial to provide a regulated current based upon the actual characteristics of the drive control element. An example of such a system is a nuclear reactor rod control system. In a rod control system, the position of the rods is typically controlled by electro-magnets. The power for these electro-magnets is derived from three phase AC power. To accurately regulate the current driving the electro-magnets and thus the control rod position, it is desirable to monitor the phase periods of the AC power. Monitoring the AC power phase period, however, does not provide control adapted to the characteristics of the drive control system.